The New York City Subway is a rapid transit system owned by the City of New York and leased to the New York City Transit Authority, a subsidiary agency of the Metropolitan Transportation Authority and also known as MTA New York City Transit. It is one of the oldest and most extensive public transportation systems in the world, with 468 stations in operation (421, if stations connected by transfers are counted as single stations); 209 mi (337 km) of routes, translating into 656 miles (1,056 km) of revenue track; and a total of 842 miles (1,355 km) including non-revenue trackage. In 2011, the subway delivered over 1.640 billion rides, averaging over five million (5,284,295 rides) on weekdays, over three million (3,033,660 rides) on Saturdays, and over two million (2,367,261 rides) on Sundays.

The New York City Subway is the seventh busiest rapid transit rail system in the world in annual ridership, after Tokyo's, Moscow's, Beijing's, Shanghai's, Seoul's, and Guangzhou's rapid transit systems, and the busiest in the Americas. It is one of the four systems in the U.S., along with portions of the Chicago 'L' system, PATH, and PATCO, to offer service 24 hours a day, 365 days a year.